1. Field of the Invention
The present invention relates to a method and a system of optimum call distribution, and particularly, to a method and a system of optimum call distribution in an intelligent network which comprises a plurality of telephone switching nodes, referred as service switching points (SSPs), for carrying out call switching/connection operation and at least one computer node, referred as service control point (SCP), for performing routing control with communicating with the SSPs to decide optimum destination for a requested call.
2. Description of the Related Art
A conventional automatic call distribution system is disclosed in several Japanese Patent Applications. For example, Japanese Patent Application Laid-open No. Hei 2-309791 "Automatic call distribution system", Laid-open No. Hei 7-283876 "Automatic terminating call distribution system using an ISDN" and Laid-open No. Hei 8-56258 "Telephone call establishing method in an intelligent network", are some of them.
Japanese Patent Application Laid-open No. Hei 2-309791 proposes a simple automatic call distribution system which is applicable to a private branch telephone exchange with low cost. That is, an external apparatus is provided to monitor busy/idle state of each extension telephone and controls optimum call termination of calls from the central telephone office to extension telephone appropriately.
Japanese Patent Application Laid-open No. Hei 7-283876 proposes an automatic terminating call distribution system using special functions of the ISDN such as the user-user information transfer function and the call transfer function between a private branch telephone exchange and ISDN terminals. That is, a call to be terminated to the private branch telephone exchange is distributed to one of ISDN terminals using the call transfer function, and various kinds of information can be transmitted by the user-user information transfer function.
Japanese Patent Application Laid-open No. Hei 8-56258 proposes a system in which a telephone call in an intelligent network is processed and established by an intelligent terminal in cooperation with structural components of the intelligent network such as a database including information with regard to calls.
As described in the above, in a conventional call distribution system, a telephone switching system itself or a special terminal monitors a busy/idle state of a circuit or a circuit group for call destination, or routing is controlled by an intelligent terminal connected to a telephone switching system, or special functions of the ISDN is used for distributing a call. Therefore, optimum selection of a terminating address networkwide, that is, over all circuits or all circuit groups connected to a network is not possible.